Monascus-fermented rice is a reddish purple rice starter prepared from rice fermented by Monascus. Monascus-fermented rice, which is called red yeast rice in ancient times, is prepared by fermenting rice which is inoculated with a rice raw starter or a distiller's yeast mainly containing Monascus. Monascus-fermented rice is red, thus it is also called red koji, red rice, distilled grains, and is also known as Fujian yeast and Fujian Rice etc. because it is produced in places like Fujian etc.
Monascus-fermented rice, which is a traditional Chinese medicine for both diet and therapy, has been widely applied in aspects of food coloring, wine making, fermentation and traditional Chinese medicines in ancient times. There are records including “red yeast rice, non-toxic with sweet taste and neutral nature” and “spleen-tonifying, vital energy-replenishing and spleen and stomach-warming” in Principles of Correct Diet; “sweet, mild and non-toxic” and “for treatment of women dysmenorrhea and postpartum lochiorrhea, and ground with wine for drinking to achieve good effect” in Compendium of Materia Medica, and “blood-activating, digestion-improving, spleen-tonifying and stomach-warming, for treatment of diarrhea with bloody and purulent stool and traumatic injury” etc. in A Supplement to Augmented Materia Medica. 
Since Japanese professor Endo separated a physiological active substance monacolin K from Monascus ruber for the first time in the 1970s, many scholars at home or abroad have constantly found physiological active substances in Monascus metabolites including monacolin compounds, Monascus pigment, an anti-hypertension constituent γ-Aminobutyric acid (GABA) and an antioxidant constituent dimerumic acid as well as some terpenoids separated recently etc. With the development of modern biochemistry and pharmacology, effects including hypertension reduction, blood sugar reduction, obesity resistance, cancer resistance and prevention and treatment of Alzheimer's disease and osteoporosis etc. have been explored continually to add new contents to traditional Monascus-fermented rice. However, since there are various constituents in Monascus-fermented rice, people still know little about the effect of each constituent of Monascus-fermented rice, which limits scientific use of Monascus-fermented rice to a certain extent and hampers wide application of Monascus-fermented rice.